biofuel
This page provides supporting information (SI) prepared for the manuscript "Winter rye biomass can be an abundant and affordable US energy resource." It summarizes research developed through collaboration between USDA and Penn State winter rye subject matter experts and economists from ORNL's Bioresource Science and Engineering Group.
We obtained 14-year average winter rye yield simulations from the RyeGro soil-plant-atmosphere model previously developed for 30 US locations and six planting and harvesting date scenarios (Feyereisen et al. 2013). We used county-level regression model yields for the scenarios where cereal rye is planted 2 days after the prior corn grain or soybean harvest, and the subsequent corn or soybean crop is planted 7 days after the rye harvest on land in continuous corn and corn/soy rotation. These county-scale winter rye yields were inputs (SI.1) for the POLYSYS economic model (Ugarte and Ray 2000) used to estimate future agricultural biomass supplies for the DOE 2023 Billion-Ton Report (DOE 2024). Regional agronomic budget inputs (e.g., fertilizer and seeding rates, labor and machinery costs) were developed based on Malone et al. (2023) and the assumption that rye would be harvested and hauled wet in a wagon to an on-farm pit or silage bunker rather than being baled (SI.2).
Modeled fertilizer applications were 45 kg/ha of N, 15 kg/ha of P, and 56 kg/ha of K (41 lbs/acre of N, 13 lbs of P and 50 lbs/ac of K). The N fertilizer application rate was based on results from several studies across 6 states in the midwestern and southeastern US where responses to N fertilization rates from 0 to 120 kg/ha were mixed (Malone et al. 2022; Malone et al. 2023, Crespo et al. 2025; Balkcom et al. 2018). In a 13-year randomized plot trial, Crespo et al. (2024) observed that winter rye shoot biomass responded to both warmth (growing degree days) and precipitation. In a two-year trial with adequate rainfall both years, Crespo et al. (2025) observed that rye responded more to warmer spring temperatures than to N fertilizers. In a cool spring with yields < 3 Mg/ha supplemental N fertilization did not improve yields compared with natural N mineralization from soil organic matter (0 fertilizer N), but in a warmer spring when there were sufficient growing degree days, supplemental N fertilizer at 30 and 60 kg N/ha resulted in higher yields. While we used the midpoint of 30 and 60 kg/ha (45 kg N/ha) for this study’s national projections, location-specific fertilizer recommendations should be based on local climate and soil conditions.
Western US counties where evaporation exceeds precipitation were excluded from consideration since our budgets do not account for irrigation; unirrigated rye in these areas would consume soil water needed for corn and soybeans. In the eastern US with ample spring soil water, we assumed rainfed winter rye even if the summer crop is irrigated; so winter rye was allowed in these counties if profitable given county yields and costs.
We started POLYSYS with the 2023 USDA agricultural baseline and ran the model out to 2041 with annual timesteps and price intervals to simulate a mature market demand for biomass. Winter rye production was limited to locations where the net returns of corn/rye/soy rotations were greater than the net returns from corn/soy rotations. County-level biomass estimates (SI.3) and production areas (SI.4) are summarized here for three biomass farmgate rice offerings in dollars per dry US short ton: $30/dt, $70/dt, and $150/dt. At a price offering of $150/dt ($165/Mg), we found a potential winter rye biomass supply of 214 M dry short tons (194 million Mg) produced across 80.7 million acres (32.7 million ha).
We modeled winter rye production relative to a “pessimistic case” of 10% lower rye yields and 10% higher production costs relative to an “optimistic case” of 10% rye yield improvements and 10% lower production costs (SI.5). With improvements in crop yield and harvesting efficiency, winter rye biomass production could increase to 230 million Mg yr-1. We then compared the economic returns and acreages of winter rye to other bioenergy crops and residues recently modeled for DOE's national biomass resource assessment. We found that winter rye is competitive with other cellulosic feedstocks across a range of prices and can produce more biomass at a lower cost than perennial grasses (switchgrass and miscanthus), crop residues (corn stover and wheat straw), and woody biomass (poplar and willow) (SI.5).
Because this crop is grown on land that would otherwise be fallow, we found that high price offerings and large volumes of winter rye would have little or no impact on national 20-year average equilibrium food crop prices (SI.6). Winter rye is easier to establish and remove than perennial crops like miscanthus or willow, meaning that it has lower risk and is more likely to expand across acres than other dedicated energy crops (SI.7).
We calculated energy and fertilizer yields from the potential 194 million Mg annual biomass supply at a price offering of $165/Mg by assuming the rye was anaerobically digested to produce renewable natural gas (RNG). We used previously published biogas production rates (Herbstritt et al. 2022) and calculated net energy based on both agronomic and digester operations as well as an average round trip transportation distance of 129 km to a centralized digester (SI.2). For this biomass production quantity, annual bioenergy yields would be 1.59 EJ per year (SI.8). If all of this winter rye were converted to natural gas through anaerobic digestion, we estimate that there would be enough nitrogen in the digestate to recover 1.3 million Mg of N fertilizer (SI.8).
The 8 referenced file attachments of supporting information (SI) are provided below the Citations. Additional POLYSYS outputs for the Winter Rye scenarios exceed the 8 MB file size limit for this site but are available upon request. Please contact biokdfadmin@ornl.gov for access.
Citations:
Balkcom, K.S., Duzy, L.M., Arriaga, F.J., Delaney, D.P. and Watts, D.B. (2018), Fertilizer Management for a Rye Cover Crop to Enhance Biomass Production. Agronomy Journal, 110: 1233-1242. https://doi.org/10.2134/agronj2017.08.0505.
Crespo, C., Malone, R. W., Radke, A., Kovar, J. L., Emmett, B. D., Feyereisen, G. W., Thorp, K. R., Richard, T., & O'Brien, P. L. (2025). Rye performance in central Iowa under different seeding and nitrogen fertilizer rates. Agronomy Journal, 117, e70112. https://doi.org/10.1002/agj2.70112.
Crespo, C., O’Brien, P. L., Ruis, S.J., Kovar, J.L., Kaspar, T.C. (2024). Thermal time and precipitation dictate cereal rye shoot biomass production, Field Crops Research 315, https://doi.org/10.1016/j.fcr.2024.109473.
Feyereisen, G. W., G.T.T. Camargo, R.E. Baxter, J.M. Baker, and T.L. Richard (2013). Cellulosic biofuel potential of a winter rye double crop across the US corn-soybean belt. Agronomy Journal 105(3):631-642.
Herbstritt S., T. L. Richard, S. H. Lence, H. Wu, P. L. O’Brien, B. D. Emmett, T. C. Kaspar, D. L. Karlen, K. Kohler, and R. W. Malone (2022). Rye as an energy cover crop: management, forage quality, and revenue opportunities for feed and bioenergy. Agriculture 12:1691.
Malone, R.W., O’Brien, P.L., Herbstritt, S., Emmett, B.D., Karlen, D.L., Kaspar, T.C., Kohler, K., Radke, A., Lence, S.H., Wu, H., and Richard, T.L. (2022). Rye soybean double-crop: planting method and N fertilization effects in the North Central US. Renewable Agriculture and Food Systems 1–12. https://doi.org/10.1017/S1742170522000096
Malone R.W., A. Radke, S. Herbstritt, H. Wu, Z. Qi, B. D. Emmett, M. J. Helmers, L. A. Schulte, G. W. Feyereisen, P. L. O’Brien, J. L. Kovar, N. Rogovska, E. J. Kladivko, K. R. Thorp, T. C. Kaspar, D. B. Jaynes, D. L. Karlen, and T. L. Richard (2023). Harvested winter rye energy cover crop: Multiple benefits for North Central US. Environmental Research Letters 18:(7), 074009.
Ugarte D.G. and D. E. Ray (2000). Biomass and bioenergy applications of the POLYSYS modeling framework. Biomass and Bioenergy 18(4), 291-308.
US Department of Agriculture (USDA). Agricultural Projections to 2034. Office of the Chief Economist, World Agricultural Outlook Board, US Department of Agriculture. Prepared by the Interagency Agricultural Projections Committee. Long-Term Projections Report OCE-2025-1, 114 pp. (2025).
US Department of Energy (DOE). 2023 Billion‐Ton Report: An Assessment of US Renewable Carbon Resources. M. H. Langholtz (Lead). Oak Ridge, TN: Oak Ridge National Laboratory. ORNL/SPR-2024/3103 (2024). https://www.energy.gov/eere/bioenergy/2023-billion-ton-report-assessmen…
US Department of Agriculture (USDA). Agricultural Projections to 2034. Office of the Chief Economist, World Agricultural Outlook Board, US Department of Agriculture. Prepared by the Interagency Agricultural Projections Committee. Long-Term Projections Report OCE-2025-1, 114 pp. (2025).
This project contributes to understanding and enhancing socioeconomic and environmental benefits of biofuels through modeling the effect of prices and policy incentives on fuel markets for “hard-to-decarbonize” transportation sectors. The main analytical tool used in this project is the BioTrans model, originally developed to assess and quantify the economic and energy security benefits of biofuels for light-duty vehicles and bioproducts. This project restructured and updated the BioTrans model to assess biofuels for the hard-to-decarbonize transportation sectors such as the aviation and shipping.
The BioTrans model is a market equilibrium model assessing the biofuel supply chain for a 30-year horizon with annual periods. It is a national (United States) model and has states as its spatial units. The model maximizes social surplus, which implies minimizing the costs, while meeting transportation fuel demands. While it takes transportation fuel markets into account endogenously, land allocation decisions and non-biofuel uses of biomass are considered exogenously. The model considers potential synergies or competition for the use of biomass among the different transportation segments as well as the competition between new biofuels and incumbent petroleum-based fuels.
The diagram in Figure 1 summarizes the main components included in BioTrans as of September 2025.
Figure 1. Main components included in BioTrans
The biomass feedstocks and petroleum products in blue rectangles are those for which the model includes supply curves, and the transportation segments in red boxes are those for which the model includes demand curves. The intermediate activities reflect the steps required to convert biomass into biofuel, and the intermediate products are biofuels required for blending and retail. Each commodity must satisfy a material balance equation so that its sources and sinks match with each other.
The ability to explore the interaction of federal and state-level biofuel policies and their impact on the volume and mix of biofuels produced in the United States is one of the key attributes of the model. Figure 2 shows the list of federal and state-level biofuel-related policies and incentives contained in the BioTrans model as of September 2025.
Figure 2. Federal and state-level biofuel-related policies and incentives
The code for the BioTrans model is available at https://code.ornl.gov/bioenergy/biotrans_model
This workshop examines the potential benefits, feasibility, and barriers to the use of biofuels in place of heavy fuel oil (HFO) and marine gas oil for marine vessels. More than 90% of world’s shipped goods
travel by marine cargo vessels powered by internal combustion (diesel) engines using primarily low-cost residual HFO, which is high in sulfur content. Recognizing that marine shipping is the largest source of
anthropogenic sulfur emissions and is a significant source of other pollutants including particulates, nitrogen oxides, and carbon dioxide (CO2), the International Maritime Organization enacted regulations to
lower the fuel sulfur content from 3.5 wt.% to 0.5 wt.% in 2020. These regulations require ship operators either to use higher-cost, low-sulfur HFO or to seek other alternatives for reducing sulfur emissions (i.e.,
scrubbers, natural gas, distillates, and/or biofuels). The near-term options for shipowners to comply with regulations include fueling with low-sulfur HFO or distillate fuels or installing emissions control systems.
However, few refineries are equipped to produce low-sulfur HFO. Likewise, the current production rates of distillates do not allow the necessary expansion required to fuel the world fleet of shipping vessels
(which consume around 330 million metric tons). This quantity is more than twice that used in the United States for cars and trucks. The other near-term option is to install emission control systems, which also
requires a significant investment. All of these options significantly increase operational costs. Because of such costs, biofuels have become an attractive alternative since they are inherently low in sulfur and
potentially also offer greenhouse gas benefits. Based on this preliminary assessment, replacing HFO in large marine vessels with minimally processed, heavy biofuels appears to have potential as a path to
reduced emissions of sulfur, CO2, and criteria emissions. Realizing this opportunity will require deeper knowledge of (1) the combustion characteristics of biofuels in marine applications, (2) their compatibility
for blending with conventional marine fuels (including HFO), (3) needs and costs for scaling up production and use, and (4) a systems assessment of their life cycle environmental impacts and costs. It is
recommended that a research program investigating each of these aspects be undertaken to better assess the efficacy of biofuels for marine use.
The economic potential for Eucalyptus spp. production for jet fuel additives in the United States
The economic potential for Eucalyptus spp. production for jet fuel additives in the United States: A 20 year projection suite of scenarios ranging from $110 Mg-1 to $220 Mg-1 utilizing the POLYSYS model.
Biofuel impacts on biodiversity and ecosystem services
The development of modern high efficiency bioenergy technologies has the
potential to improve energy security and access while reducing environmental impacts
and stimulating low-carbon development. While modern bioenergy production is
increasing in the world, it still makes a small contribution to our energy matrix.
At present, approximately 87% of energy demand is satisfied by energy produced
through consumption of fossil fuels. Although the International Energy Agency (IEA)
predicts that this share will fall to 75%, the total consumption of fossil fuels will continue
to rise, adding another 6 Gt of carbon to the atmosphere by 2035. The consequences
of this increase are worrisome.
Our oceans are being critically affected. Oceans are an important CO2 sink and absorb
26% of the CO2 emissions but due to accelerated acidification and rising sea surface
temperatures, this capacity may be reduced. Never in the last 300 million years has
the rate of ocean acidification been so high. In the last 150 years, acidity in oceans
increased by 30%. The main cause are the emissions from fossil fuel burning, especially
the release of CO2.
Deforestation and land degradation also contribute to increased greenhouse gas
emissions. The world’s total forest area in 2010 was just over 4 billion hectares,
which corresponds to an average of 0.6 ha per capita. Each year, between 2000 and
2010, around 13 million hectares of forestland were converted to other uses or lost
through natural causes. The production of timber for housing or the need to make land
available for urbanization, large-scale cash crops such as soy and oil palm, subsistence
agriculture and cattle ranching induce deforestation. Forests are also degraded or
damaged due to the soaring demand for fuelwood and charcoal for cooking and heating
in developing countries that suffer from low levels of access to modern energy services.
Most of the world’s bioenergy is presently derived from wood burning for cooking and
heating in developing countries. Such traditional uses of biomass are low in cost to the
users, but their technical inefficiency results in considerable health and environmental
costs while providing only low quality energy services. Many countries demonstrate
that a much higher efficiency can be obtained in traditional uses commercially with
sustainably managed feedstock supplies. Since bioenergy systems often operate
at the interface between agriculture and forestry, they are also closely connected to
the planning and governance of these sectors and of policy to conserve and manage
forests. Consequently, interdisciplinary and cross-level or horizontal studies are needed
in order to define the best routes through which achieve a sustainable energy matrix.
Can modern bioenergy make a significant contribution to our energy matrix with
positive contributions to the environment? What are the social, environmental and
economic implications of the expansion of bioenergy in the world? How does expansion
of bioenergy perform in the context of the food, energy, climate, development and
environment nexus? Which are the most significant potential benefits of bioenergy
production and use and how can we design implementation platforms and policy
frameworks to ensure that such benefits are realized and widely replicated? What are
the scientific research needs and technological development requirements needed to
fill in the gaps?
To answer some of these questions, FAPESP BIOEN, Climate Change and BIOTA
Research Programs led, in December 2013, a group of 50 experts from 13 countries
convened at UNESCO in Paris, France, for a rapid assessment process on “Bioenergy
and Sustainability” under the aegis of SCOPE. Background chapters commissioned
before the workshop provided the basis for this international consultation during which
crosscutting discussions focused on four themes: Energy Security, Food Security,
Environmental and Climate Security, Sustainable Development and Innovation.
The resulting synthesis volume has the contribution of 137 researchers from 82
institutions in 24 countries.
A causal analysis framework for land-use change and the potential role of bioenergy policy
We propose a causal analysis framework to increase understanding of land-use change (LUC) and the reliability of LUC models. This health-sciences-inspired framework can be applied to determine probable causes of LUC in the context of bioenergy. Calculations of net greenhouse gas (GHG) emissions for LUC associated with biofuel production are critical in determining whether a fuel qualifies as a biofuel or advanced biofuel category under regional (EU), national (US, UK), and state (California) regulations. Biofuel policymakers and scientists continue to discuss to what extent presumed indirect land-use change (ILUC) estimates should be included in GHG accounting for biofuel pathways. Current estimates of ILUC for bioenergy rely largely on economic simulation models that focus on causal pathways involving global commodity trade and use coarse land-cover data with simple land classification systems. This paper challenges the application of such models to estimate global areas of LUC in the absence of causal analysis. The proposed causal analysis framework begins with a definition of the change that has occurred and proceeds to a strength-of-evidence approach that includes plausibility of relationship, completeness of causal pathway, spatial co-occurrence, time order, analogous agents, simulation model results, and quantitative agent–response relationships. We discuss how LUC may be allocated among probable causes for policy purposes and how the application of the framework has the potential to increase the validity of LUC models and resolve controversies about ILUC, such as deforestation, and biofuels.
Potential Avenues for High Biofuels Penetration in the U.S. Aviation Market, Supplemental Tableau Workbook
Potential Avenues for High Biofuels Penetration in the U.S. Aviation Market, Supplemental Tableau Workbook, 2016
Emily Newes, National Renewable Energy Laboratory Jeongwoo Han, Argonne National Laboratory Steve Peterson, Lexidyne LLC
Advanced Feedstock Supply System Validation Workshop Summary Report
Conventional feedstock supply systems exist and have been developed for traditional agriculture and forestry systems. These conventional feedstock supply systems can be effective in high biomass-yielding areas (such as for corn stover in Iowa and plantation-grown pine trees in the southern United States), but they have their limits, particularly with respect to addressing feedstock quality and reducing feedstock supply risk to biorefineries. They also are limited in their ability to efficiently deliver energy crops. New logistics technologies and systems are needed to address these challenges and support a growing bioenergy industry.
The proposed solution put forth by the DOE Bioenergy Technologies Office to address these challenges is Advanced Feedstock Supply Systems. The Advanced Feedstock Supply Systems incorporate densification, drying, and other preprocessing technologies to create a biomass commodity. A feature of these advanced systems is biomass preprocessing depots that format biomass in fairly close proximity to the location of production. However, validating assumptions used to develop these advanced systems is critical.
The Advanced Feedstock Supply System Validation Workshop gathered experts from industry, DOE offices, DOE-funded laboratories, and academia to discuss approaches to addressing challenges associated with an expanding bioenergy industry and assumptions used in the Advanced Feedstock Supply System. The workshop was sponsored by the DOE Bioenergy Technologies Office.
Incorporating Bioenergy into Sustainable Landscape Designs
The paper describes an approach to landscape design that focuses on integrating bioenergy production with their components of environmental, social and economic systems. Landscape design as used here refers to a spatially explicit, collaborative plan for management of landscapes and supply chains. Landscape design can involve multiple scales and build on existing practices to reduce costs or enhance services. Appropriately applied to a specific context, landscape design can help people assess trade-offs when making choices about locations, types of feedstock, transport, refining and distribution of bioenergy products and services. The approach includes performance monitoring and reporting along the bioenergy supply chain. Examples of landscape design applied to bioenergy production systems are presented. Barriers to implementation of landscape design include high costs ,the need to consider diverse land-management objectives from a wide array of stakeholders, up-front planning requirements, and the complexity and level of effort needed for successful stakeholder involvement. A landscape design process maybe stymied by insufficient data or participation. An impetus for coordination is critical, and incentives may be required to engage landowners and the private sector. Hence devising and implementing landscape designs for more sustainable outcomes require clear communication of environmental, social, and economic opportunities and concerns.</p>
Bioenergy and Biodiversity: Key Lessions from the Pan American Region
Understanding how large-scale bioenergy production can affect biodiversity and ecosystems is important if society is to meet current and future sustainable development goals. A variety of bioenergy production systems have been established within different contexts throughout the Pan American region, with wide-ranging results in terms of documented and projected effects on biodiversity and ecosystems. The Pan American region is home to the majority of commercial bioenergy production and therefore the region offers a broad set of experiences and insights on both conflicts and opportunities for biodiversity and bioenergy. This paper synthesizes lessons learned focusing on experiences in Canada, the United States, and Brazil regarding the conflicts that can arise 6between bioenergy production and ecological conservation, and benefits that can be derived when bioenergy policies promote planning and more sustainable land-management systems. We propose a research agenda to address priority information gaps that are relevanLive t to biodiversity concerns and related policy challenges in the Pan American region.